1. Field
Apparatuses and methods consistent with the present inventive concept relate to a device and method for monitoring radiation exposure, and more particularly, a wearable radiation detection device, and method of controlling the same, for monitoring a wearer's exposure to ultraviolet A (UVA) and ultraviolet B (UVB) radiation.
The ultraviolet (UV) region covers the spectral wavelength range 100-400 nm and is divided into three bands: UVA (315-400 nm) UVB (280-315 nm) and UVC (100-280 nm). As sunlight passes through the atmosphere, UVC radiation and approximately 90% of UVB radiation are absorbed by ozone, water vapor, oxygen and carbon dioxide. By contrast, UVA radiation is less affected by the atmosphere, and is able to penetrate the atmosphere to a larger extent. As a result, the UV radiation reaching the Earth's surface is largely composed of UVA radiation with a small component UVB radiation.
Unfortunately, the majority of people are unaware that years of exposure to the sun are cumulative, and ultimately damage the skin. The UV rays of the sun cause degenerative changes in the dermis that result in premature aging from the loss of the elasticity, this leads to thinning, wrinkling, and drying of the skin. Prolonged and repeated sun exposure has been shown to be a major factor in pre-cancerous and cancerous lesions. Studies have shown that UVB radiation may be a key factor in the development of skin cancer—whereas ultraviolet UVA radiation augments the carcinogenic effects of UVB.
The skin is the largest organ of the body and its primary function is to protect the underlying tissue by acting as a surface barrier to the external environment. The epidermis, or the outer layer of the skin, contains melanocytes that produce melanin, a pigment that protects the body from injurious ultraviolet rays. A fair-skinned person, one who has smaller amounts of melanin, should be especially cautious about excessive sun exposure. Even on overcast days, since up to 80% of the UV rays penetrate through the clouds, serious sunburns can occur. Some sunscreens may filter some UVA and most UVB rays, but a sunscreen that blocks all UVA is presently not available.
Moreover, certain topical and systemic medications enhance the sun's effect, even with brief exposure. The chemicals in these medications absorb light and release energy that harms cells and tissue. This is known as drug-induced photosensitivity and the result is unwanted sunburns. Drugs that may cause photosensitivity are: (i) Antidysrythmics, e.g., Amiodorone, Quinidine Antihistamines, Diphenhydramine (Benedryl), Anti-infectives, Sulfonamides, Tetracyclines, Chloroquine, Griseofulvin, Nalidixic Acid, Antineoplastics—Chemotherapy Medications, Dacarbazine, Methotrexate, Fluorouracil (5FU); (ii) Diuretics, e.g., Thiazides, Chlorothiazides and (iii) Psychotherapeutics, e.g. Chlorpromazine, Chlorothiazides, Promazine, Thioridazine, Sulfonylureas.
Other issues of concern regarding UV exposure include the potential for intraocular damage, e.g., increased risk of cataracts. Consequently, protective eyewear and limited exposure are recommended.
Additionally, some individuals are particularly sensitive to UV radiation exposure. For example, post-cosmetic surgery patients must closely monitor their exposure time to UVA rays, and particularly, with chemical facelift and chemical-peel procedures. In this case, because of the reduction of melanin due to the cosmetic procedure, a patient might well be advised to avoid sunlight up to six months in order to prevent hyperpigmentation.
The Food and Drug Administration (FDA) has rated popular sunscreen products according to their sun protection factor (SPF). This is a method of measuring the effectiveness of sunscreen filtering and absorption of UVB radiation. Previously, there was no similar rating of products to screen UVA radiation. New FDA regulations require new labels on sunscreens that do not protect from UVA radiation to be labeled “Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has only been shown to prevent sunburn, not skin cancer or early skin aging.” If the sunscreen blocks both UVA radiation, it will include ingredients such as titanium dioxide, inc oxide, avobenzone and mexoryl SX and be labeled as “Broad Spectrum.” Beginning in 2013, the FDA will recognize the words “Broad Spectrum” on sunscreens packaging, as “Broad Spectrum” indicates a wide range of absorbance, including both UVA and UVB wavelengths. Nevertheless, the best ways to avoid overexposure of UV rays is to cover and protect skin and eyes, as well as limit the time spent exposed to UV rays as much as possible.
Other not-so-well-known maladies or conditions exasperated by over-exposure of UVA and UVB are briefly enumerated here: (i) contact dermatitis, e.g., poison ivy, poison oak, allergic rash, photo dermatitis and discoid lupus erythematosus; (ii) prior heat exhaustion/stroke. If a patient has had a previous diagnosis of heat exhaustion, afterward they are more susceptible to heat stroke than before. People who work in the sun, e.g., postal carriers and construction workers, would benefit by being able to monitor how much exposure they receive in order to prevent the development of heat stroke; (iii) rosacea; (iv) radiation patients; and (v) head/neck cancer.
Furthermore, other conditions that are sensitive to over exposure of UVA and UVB include (i) chemotherapy drugs, (ii) some antibiotics such as doxycycline and tricyclic antidepressants; (iii) increased risk for macular damage that could lead to macular degeneration; (iv) increased risk for development of cataracts; and (v) increased risk for melanoma.
In patients that suffer from seasonal affect disorder, some sun exposure is helpful for them, but if there were other diagnosis present that requires limited exposure, it would be beneficial to monitor how much exposure they are actually receiving.
Erythema, or skin redness caused by inflammation, is the most widely used clinical endpoint in human skin photobiology. Erythema is also used in determining the sun protection factor (SPF) of sunscreens. Despite its widespread use, little is known of the basic biology of ultraviolet radiation (UVR)-induced erythema.
Individual sensitivity to UVR is assessed by the minimal erythema dose (MED), most often 24 hours after irradiation. The MED is defined as the lowest UVR dose that will cause either a just perceptible redness or redness with a definite border. One study has shown that the former definition is more reliable.
Several workers have determined action spectra (i.e., relative effectiveness at different wavelengths) for the MED in human skin using “monochromatic” radiation, in reality narrow-to-broad-spectrum radiation, from a monochromator. Some earlier studies have been pooled to generate a reference erythema action spectrum that has been adopted by the Commission Internationale de l'Eclairage (CIE). These studies show that UVB (280-315 nm) is orders of magnitude more effective per unit dose (J/m2) than UVA (315-400 nm). For example, the median MED at 300 nm is 0.025 J/cm2, whereas exposure at 360 nm is 32 J/cm2. A comparison of the action spectra for erythema and epidermal DNA photodamage provides strong circumstantial evidence that DNA is a major chromophore for erythema. Studies indicate that the most destructive wavelengths for most biological organisms are between 305 nm and 310 nm.
The global solar UV Index (UVI) describes the level of solar UV radiation at the Earth's surface. The values of the index range from zero upward—the higher the index value, the greater the potential for damage to the skin and eye, and the less time it takes for harm to occur.
The global solar UVI is a simple measure of the UV radiation level at the Earth's surface and an indicator of the potential for skin damage. It serves as an important vehicle to raise public awareness and to alert people about the need to adopt protective measures when being exposed to UV radiation. The UVI was developed through an international effort by the World Health Organization (WHO) in collaboration with the United Nations Environment Program (UNEP), the World Meteorological Organization (WMO) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
UV radiation levels, and therefore the values of the index, vary throughout the day. In reporting the UVI, most emphasis is placed on the maximum UV radiation level in a given day. This occurs during the four-hour period around solar noon. Depending on geographical location and whether daylight saving time is applied, solar noon takes place between local noon and approximately 2:00 p.m. News/weather media usually present a forecast of the maximum UVI radiation level for the following day.
According to the Skin Cancer Foundation about 90% of non-melanoma and about 65% melanoma skin cancers are associated with ultraviolet (UV) radiation from the sun. About 700,000 new cases are diagnosed each year, and the numbers are rising despite the increased use of sunscreen. Additionally, according to the Skin Cancer Foundation, vitamin D is essential for bone health, immune system functioning, and a lack of it puts us at risk for painful weak muscles, inadequate bone mineralization and skeletal deformities in children as well as mineral loss and soft bones in adults. Our bodies manufacture vitamin D when the sun's UVB rays interact with 7-dehydrocholesterol present in the skin [ . . . ] a few minutes at midday are sufficient for many Caucasians [ . . . ] after reaching the production limit, further exposure actually destroys the vitamin, decreasing vitamin D levels. The Mayo Clinic also states that vitamin D, which comes mainly from sun exposure, is responsible for many health-promoting properties such as cancer prevention, inflammation reduction, etc. Therefore, there is a need to balance the benefits versus the risks of exposure, and optimal limits on exposure are desirable.
2. Description of Related Art
Various patents are known which disclose disposable dosimeters designed to warn about the amount of sun radiation absorbed, and thus to inform an individual when she should terminate exposure to sun radiation. However, such related art systems are lacking in both durability and versatility due to their overly simplistic design.
In view of this, it can be seen that there is a need for a UVA and UVB radiation monitoring aid that can be used on a daily basis in order to provide the user with reliable information about the permissible duration of exposure to sun radiation irrespective of the user's skin type, season, and other atmospheric conditions, i.e., allow for personal customization. Further, it is desirable to provide a reliable system which is capable of being worn for extended periods by many different types of individuals under a variety of environmental conditions.